I. Field of the Invention
This invention relates generally to a machining lathe. More specifically, this invention relates to an improved tool block slide assembly for clamshell pipe and shaft machining lathes that is particularly designed to shield the moving parts thereof from metal chips being removed from the workpieces that might otherwise jam the slide mechanism.
II. Description of the Prior Art
The general concept of automated clamshell-type lathes is well known in the art. One such lathe is shown and described in U.S. Pat. No. 5,549,024 that was granted to the present applicant. Various advantages of that machining lathe over earlier lathes are outlined in that patent's specification.
Lathes of the type described in the above-referenced patent are often used in environments, such as in a nuclear power plant, where it is of utmost importance to minimize the amount of time that an operator is at the jobsite. By minimizing the amount of time, the amount of radiation that the operator receives is reduced. If the goal is to reduce the amount of exposure to radiation, it is then imperative that the machining lathe for cutting and/or refurbishing pipes and pipe flanges be designed and built so that the chance of any breakdown of the lathe equipment is minimized. Any breakdown of the equipment requiring operator repair or replacement increases the amount of radiation to which the operator is exposed.
While clamshell-type machining lathes such as described in the above-cited Ricci '024 patent are highly effective in reducing the amount of time that the operator is on the jobsite, the possibility exists that chips of metal being machined can find their way into the tool block slide assembly and thus interfere with movement of the tool block slide that clamps and holds the carbide-tipped cutting tool. Moreover, the mechanism for imparting rotation to the feed screw in the device described in the Ricci '024 patent comprises a starwheel drive. As the tool bit slide assembly that is mounted on the rotatable ring of the clamshell lathe orbits the workpiece, a tooth on the starwheel engages a stationary pin and imparts rotation to the feed screw on which the starwheel is mounted. It has been found from experience that such starwheel drives are somewhat prone to frequent failure and also that the depth of cut varies somewhat, leaving the surface being machined slightly irregular.
The present invention addresses these problems associated with prior art clamshell machining lathes and provides a new and improved tool block slide assembly. The new slide assembly offers a unique arrangement which greatly reduces the possibility of particles milled from a workpiece finding their way into the tool block slide assembly where they could interfere with movement of the slide. Moreover, it is designed for longer service life, easier set-up and reduced variation in cutting depths, leaving a smoother machined surfaces on the workpieces involved by eliminating the star wheel tool block slide and replacing it with a cam lever actuated mechanism.